Table 2. Descriptive statistics of inter- and intra-fractional variations.

		Average ± SD	range	Average ±SD	range
				(by absolute value)
Inter-fractional variation	ΔRL (mm)	0.38 ± 1.73	-7.99 to 12.19	1.32 ± 1.19	0 to 12.19
	ΔSI (mm)	-1.02 ± 2.22	-5.53 to 23.75	1.82 ± 1.63	0 to 23.75
	ΔAP (mm)	-2.19 ± 2.16	-14.4 to 15.85	2.49 ± 1.80	0 to 15.85
	Δpitch (°)	-0.62 ± 0.96	-4.4 to 2.4	0.87 ± 0.74	0 to 4.4
	Δroll (°)	0.03 ± 1.30	-5.6 to 5.8	0.93 ± 0.91	0 to 5.8
	Δyaw (°)	-0.36 ± 1.02	-3.7 to 2.6	0.82 ± 0.71	0 to 3.7
	Δ3D (mm)	3.79 ± 2.04	0.28 to 23.80
Intra-fractional variation	ΔRL (mm)	0.01 ± 0.76	-2.89 to 2.44	0.56 ± 0.51	0 to 2.89
	ΔSI (mm)	-0.07 ± 0.64	-2.79 to 2.55	0.48 ± 0.42	0 to 2.79
	ΔAP (mm)	-0.02 ± 0.90	-4.74 to 2.99	0.67 ± 0.60	0 to 4.74
	Δpitch (°)	-0.07 ± 0.55	-2.7 to 1.6	0.40 ± 0.40	0 to 2.7
	Δroll (°)	0.05 ± 0.77	-4.2 to 2.9	0.52 ± 0.57	0 to 4.2
	Δyaw (°)	0.03 ± 0.49	-2.1 to 3.0	0.35 ± 0.35	0 to 3.0
	Δ3D (mm)	1.14 ± 0.70	0.01 to 5.66

Abbreviations: SD, standard deviation; RL, right-left; SI, superior-inferior; AP, anterior-posterior; 3D, three dimensional